A years long plot by a mysterious Cult threatens the town, and the Equestria Girls suddenly find themselves dealing with the supernatural and in a race against time. To save Canterlot, the girls, with help from an unseen ally and a certain little Spud, must put on the Proton Packs and face the coming darkness.

The mane six are summoned to Manehatten by order of Princess Celestia, in order to investigate reports of unusual paranormal activity occurring within the city. But when Fluttershy becomes targeted by a demonic entity, will the power of friendship be enough to save her? Or will more drastic measures be needed?

A ghost and an Earth Pony are plunged into an adventure together with their souls in the balance... The Great Houses of old Equesria hold dark secrets which could affect many, and as Trigger and Misty discover them, they make themselves even greater targets. Can the duo refine their new abilities soon enough to use them? Will the PGB be any match for the great evil that is rising?